ff244c6b29
syzkaller reported a double free [1], caused by the fact that tun driver was not updated properly when priv_destructor was added. When/if register_netdevice() fails, priv_destructor() must have been called already. [1] BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 CPU: 0 PID: 2919 Comm: syzkaller227220 Not tainted 4.13.0-rc4+ #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 print_address_description+0x7f/0x260 mm/kasan/report.c:252 kasan_report_double_free+0x55/0x80 mm/kasan/report.c:333 kasan_slab_free+0xa0/0xc0 mm/kasan/kasan.c:514 __cache_free mm/slab.c:3503 [inline] kfree+0xd3/0x260 mm/slab.c:3820 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 security_tun_dev_free_security+0x48/0x80 security/security.c:1512 tun_set_iff drivers/net/tun.c:1884 [inline] __tun_chr_ioctl+0x2ce6/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x443ff9 RSP: 002b:00007ffc34271f68 EFLAGS: 00000217 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443ff9 RDX: 0000000020533000 RSI: 00000000400454ca RDI: 0000000000000003 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000401ce0 R13: 0000000000401d70 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 2919: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xaa/0xd0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x101/0x6f0 mm/slab.c:3627 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:666 [inline] selinux_tun_dev_alloc_security+0x49/0x170 security/selinux/hooks.c:5012 security_tun_dev_alloc_security+0x6d/0xa0 security/security.c:1506 tun_set_iff drivers/net/tun.c:1839 [inline] __tun_chr_ioctl+0x1730/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe Freed by task 2919: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x6e/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3503 [inline] kfree+0xd3/0x260 mm/slab.c:3820 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 security_tun_dev_free_security+0x48/0x80 security/security.c:1512 tun_free_netdev+0x13b/0x1b0 drivers/net/tun.c:1563 register_netdevice+0x8d0/0xee0 net/core/dev.c:7605 tun_set_iff drivers/net/tun.c:1859 [inline] __tun_chr_ioctl+0x1caf/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe The buggy address belongs to the object at ffff8801d2843b40 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff8801d2843b40, ffff8801d2843b60) The buggy address belongs to the page: page:ffffea000660cea8 count:1 mapcount:0 mapping:ffff8801d2843000 index:0xffff8801d2843fc1 flags: 0x200000000000100(slab) raw: 0200000000000100 ffff8801d2843000 ffff8801d2843fc1 000000010000003f raw: ffffea0006626a40 ffffea00066141a0 ffff8801dbc00100 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d2843a00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8801d2843a80: 00 00 00 fc fc fc fc fc fb fb fb fb fc fc fc fc >ffff8801d2843b00: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc ^ ffff8801d2843b80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8801d2843c00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ================================================================== Fixes: cf124db566e6 ("net: Fix inconsistent teardown and release of private netdev state.") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.